A sum of ₹1200 amounts to ₹1320 in 2 years at simple interest. What is the rate of interest per annum?

ब्याज = 1320 - 1200 = ₹120। दर = (ब्याज × 100) / (मूलधन × समय) = (120 × 100) / (1200 × 2) = 5%।